Orthogonal frequency division multiple access (OFDMA) modulation is well known to have a high peak to average power (PAPR) ratio. High PAPR reduces transmitter power amplifier (PA) power efficiency, increases PA back off, which in particular reduces the uplink link budget. Therefore, it is desirable to control the PAPR for uplink transmission.
PAPR reduction for OFDMA modulation is well studied. Tone reservation (TR) is one of the promising techniques. With TR, the system reserves a set of sub-carriers for PAPR reduction. The reserved tones are not used for data transmission. Instead, when one signal has high PAPR, a complementary sequence is transmitted on the reserved tones to reduce the PAPR of the signal.
However, the TR approach has a PAPR re-growth problem: the complementary sequence, when added with the original sequence, may reduce the original peak. However, the newly generated peak may be added constructively at non-peak locations. Therefore, multiple iterations may be required to achieve the desired PAPR level with added complexity.
Thus, there is a need for a PAPR reduction scheme that overcomes the shortcomings of the prior art.